Malaysian Prime Minister Mahathir Mohamad's election win in May was a dramatic shock.

But since taking power the ruling Pakatan Harapan (Coalition of Hope) consortium has proved less than decisive. An inchoate alliance of sectional parties, not a coherent political force with a unified outlook and clear agenda, Pakatan Harapan (PH) is exasperating many of its most devoted supporters.

It needs to do more to capitalize on the election victory, which saw Mahathir and his allies defeat Prime Minister Najib Razak and take power from a coalition led by the United Malays National Organization (UMNO), the country's dominant party since independence in 1957 and bastion of the majority ethnic Malay population.

Perhaps trial-and-error gradualism rather than impetuous doctrinaire activism makes sense in these unprecedented circumstances. But PH's long-term strategic course remains vague. It is feeling its way, often uncertainly. As it does, speculation continues about the timing and implications of the political succession from the 93-year-old nationalist Mahathir to the resurrected and perhaps impatient "soft Islamist" Anwar Ibrahim. Much is unclear.

Beyond these "personality issues," PH faces deeper challenges. It has comfortably won three by-elections that have occurred since May -- including one that saw Anwar Ibrahim return to parliament and close to grasping the top job.

But its old adversaries, who have been lying low since losing power, are beginning to flex their muscles. To mark United Nations Human Rights Day in early December a now-ragged UMNO and the ever more assertive Islamist party PAS joined forces in the name of the prerogatives of ethnic Malays and other indigenous peoples (62% of the population) and Islamic supremacy. They organized a mass street demonstration against PH plans to ratify ICERD, the U.N. Charter on the Elimination of All Forms of Racial Discrimination. Even though PH had already deferred the proposals indefinitely in a rush of prudence, tens of thousands gathered for the protest in Kuala Lumpur.

For the moment, PH enjoys some breathing space. It is the beneficiary of UMNO's post-election implosion. Many UMNO elected representatives, state and federal, are defecting, some to PH parties. Virtually the entire UMNO leadership and party structure in the Borneo state of Sabah -- until recently crucial in ensuring UMNO/BN's numerical majority in parliament -- has walked away.

To growing discontent, the continuing presence in the party of both former Prime Minister Najib and his successor as UMNO head Ahmad Zahid Hamidi hangs heavy over UMNO. Both men are under a variety of criminal breach of trust indictments over their alleged roles in the financial scandals that marked the former government.

There are calls for an emergency general meeting and new party elections. Meanwhile, many unhappy UMNO members, seeing their party flounder, are gravitating toward the Islamist party PAS. As they do, the balance between the two Malay parties, long bitter rivals drawn into an uneasy entente by Najib, is shifting.

Once holding the whip hand and the reins of government power, UMNO is increasingly reduced, as in the December mass rally, to serving as PAS's subordinate adjunct. As this process proceeds, some overdue clarification and realignment of national political forces is occurring.

But the longer-term implications of this tendency are toward the polarization of Malaysian society and politics. In prospect is a brutal contest between the fragmented forces of social democratic pluralism, now awkwardly huddling together within PH, and the religiously driven Malay ethno-sectarians, now in an alliance where the remains of the old UMNO are increasingly being made the willing and even desperate instrument of PAS with its agenda of making Malaysia an explicitly Islamic state operating under shari'ah law.

The PH government arose from "bottom-up mobilization," on a steadily growing wave of civil society activism, not coherent opposition party strength; its adversaries led by PAS and a variety of Islamist NGOs and political pressure groups are now seeking to bring down the government by recourse to far more ominous and intimidatory forms of the same strategy. They seek to show that PH cannot govern, and that they can deny it the opportunity and the authority to do so.

Despite the PH retreat, the issue will not go away. The struggle over ICERD is a proxy for a contest about profound divisions in Malaysian society. At issue is not simply whether acceding to ICERD would impugn Malaysian national and legal sovereignty. To its opponents ICERD is fundamentally at odds with what they see as the key doctrinal foundations of the Malaysian state: Malay political ascendancy (ketuanan Melayu), Malay royal power, and the supremacy of Islam.

They hold that these tenets are entrenched in perpetuity within the "social contract" by which the independence Federal Constitution of 1957, later the Malaysian Constitution of 1963, was negotiated. They have so persuaded many Malaysians, including most conventional Malay voters. But this notion was artfully confected by the UMNO ideologue Abdullah Ahmad in 1986 and thereafter unilaterally retrofitted into official ideas of the Constitution. This idea of Malay ascendancy as a foundation of the nation's constitution is a brazen hoax.

In the wake of the human rights rally, serious thinkers within PH are wondering how to assuage the popular Malay anxiety, and manage the risk that disaffection could be mobilized against the new government and destroy it. What new benefits, they wonder, must be provided to the lowest 40 percent of the population, the majority of them Malays, to win their trust.

But, ever since independence in 1957 and the ensuing upheavals of 1969, it is not simply the experience and further anticipation of economic marginalization that now motivate many Malays' fear of PH and its plans. In addition to providing material benefits, PH must persuade them that they are an integral part of its view of the nation.

That will require PH strategists not just to educate them about the Malay ascendancy hoax that has been concocted to mobilize their anxieties and win their bulk political support on narrowly ethno-sectarian grounds. The PH thinkers must also craft a sustainable and, constitutionally, securely grounded notion of the Malaysian nation of today. There must be an attainable and convincing national agenda, and a coherent package of policies for its realization. Nothing less. The future of PH rests on its ability to do so.

Clive Kessler is emeritus professor of sociology and anthropology at the University of New South Wales in Sydney. He is an author who has observed Malaysia's elections since 1967, and has written extensively on Malaysia for over 50 years.